Interval training.
7/6/5/5/4/3/2/1 minute efforts with 2 minutes of active recovery after each interval. AND...
o In the first minute of each interval go hard to very hard (zone -5).
o After that first minute make the remainder of each interval progressively harder and ramp
up the effort starting at your low heart rate zone 4 on the 7 minute interval and ramp up so
that you are in your heart rate zone 5 on the 3 and 2 and 1 minute intervals.